Dynamic Inductive Charging Loop Segmentation for EV Efficiency
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Solution Overview
Problem
Current contactless charging systems for electric vehicles face inefficiencies and health risks due to high losses, radiation outside the vehicle, and inability to adapt to dynamic charging on conventional roads, especially at high speeds, as they require dedicated lanes and fail to confine magnetic radiation effectively.
Innovation Solution
A method and system for contactless charging that includes a resonant circuit with an inverter, using frequency control and phase shift measurement to optimize energy transfer, initializing the frequency to fix the phase shift sign, and employing ZVS mode for low switching losses, with adaptive frequency adjustment and noise filtering to ensure efficient and safe dynamic charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If long loops are used for contactless charging, then implementation is simplified and a single inverter can power a long stretch of road, but losses increase due to long loop lengths, radiated field heating, Joule heating, and high radiation levels
Solution Approach 1:
The patent divides the charging system into multiple small primary loops distributed along the road, each powered by its own inverter or a small group of inverters. This segmentation reduces the loop length of each individual primary circuit, thereby minimizing Joule heating losses and magnetic radiation exposure while maintaining the ability to charge vehicles over extended distances through coordinated operation of multiple segments.
2Ease of manufacture
If long loops are used for contactless charging, then implementation is simplified, but magnetic radiation is not confined and health risks arise
Solution Approach 1:
By using multiple small primary loops instead of one long loop, the magnetic field generated by each loop is localized and confined to a smaller volume directly beneath the vehicle. This segmentation prevents the accumulation and widespread radiation of magnetic fields that would occur with a long loop, thereby reducing health risks while simplifying inverter design.
Solution Approach 2:
Each small primary loop is designed to generate a localized magnetic field that is concentrated in the region directly beneath the vehicle's secondary coil. This local quality ensures that magnetic radiation is confined to where it is needed for charging, minimizing exposure to surrounding areas and reducing health risks.
3Loss of energy
If small loops are used for contactless charging, then magnetic radiation is confined and charging efficiency improves, but the system must be compatible with all road vehicles including those that cannot be charged inductively
Solution Approach 1:
The small primary loops are designed with universal compatibility in mind, allowing them to function effectively with any vehicle equipped with a secondary coil, regardless of the vehicle type or its primary charging capability. The system can charge electric vehicles inductively while remaining invisible or non-interfering to conventional vehicles, thus achieving universality across all road vehicles.
4Object-affected harmful factors
If small loops are used for contactless charging, then magnetic radiation is confined, but the loops must ensure sufficient dynamic coupling for high-speed charging with transit times around 20ms
Solution Approach 1:
The system employs dynamic tracking and control mechanisms that continuously adjust the operating parameters of the primary loops based on the real-time position and speed of the vehicle. This dynamic adaptation ensures that sufficient coupling is maintained between the primary and secondary coils even at high speeds where the vehicle traverses a loop in only about 20ms, while preserving the benefits of small loop size for magnetic radiation confinement.
Solution Approach 2:
The system uses feedback from position sensors and coupling measurements to dynamically adjust the switching frequency and power delivery of the primary loops. This feedback mechanism ensures optimal energy transfer is maintained during high-speed passage through the loop, compensating for the reduced interaction time while keeping the loops small to confine magnetic radiation.
5Loss of energy
If digital tracking method is used to maintain resonant frequency, then optimal power transfer is achieved, but the control dynamics are too slow for moving loads requiring rapid phase shift control
Solution Approach 1:
Instead of continuous digital tracking, the system uses periodic switching at predetermined frequencies that are optimized for the specific primary and secondary coil configurations. This periodic action approach maintains sufficient coupling and acceptable power transfer efficiency while enabling much faster control response times that are suitable for high-speed vehicle passage through the charging loop.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient and safe dynamic contactless charging of electric vehicles on conventional roads by reducing losses, confining magnetic radiation, and maintaining high-speed charging efficiency, with faster servo dynamics and robust noise filtering.
Implementation Method 1
electrical energy being transferred by induction between a primary coil placed on the ground and a secondary coil mounted on the vehicle
Implementation Method 2
a resonant circuit with an inverter, using frequency control and phase shift measurement to optimize energy transfer
Data Source
Figure 1~2
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AI summary
The invention relates to a method for transferring power from a primary circuit comprising a resonant circuit and an inverter to a secondary circuit of a vehicle, intended for charging by induction of a traction battery connected to said secondary circuit, said method comprising the steps: - (E6) regulating the switching cells of the primary circuit - (E2) measuring the current intensity in a primary coil -(E3) filtering a signal of said current intensity - (E4) measuring the phase difference between said current intensity and the voltage at the terminals of the resonant circuit -(E5) controlling the frequency using the previously-measured phase difference, further comprising a step (E1) of initialising the frequency of the primary circuit, capable of fixing the sign of said phase shift over a predetermined half-period of the current intensity signal, as a function of said thus initialised frequency.